System, method and apparatus for MRI maintenance and support

ABSTRACT

An MRI apparatus consolidates and stores maintenance and/or performance data automatically measured by a measurement unit and data manually input via an input device. The automatically measured data may include an adjustment value, a state value or an error record. The manually input data may include a software and/or hardware upgrade record, a customized situation record, a network connection record, a repair record, a check record, a maintenance record or an installation record, for example. Both types of data can be obtained swiftly and faults or malfunctions can be recovered from quickly or even prevented in advance. The stored data may be communicated among a plurality of MRI apparatuses, a service center apparatus and a maintenance support apparatus via a communications network.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.10/328,186, filed Dec. 26, 2002 now U.S. Pat. No. 6,972,565, the entirecontent of which is hereby incorporated by reference in thisapplication.

BACKGROUND OF THE INVENTION

The present invention relates to a system, method and apparatus forproviding maintenance and support for a magnetic resonance imaging (MRI)apparatus. In particular, the present invention is directed to a method,system and apparatus for providing preventative maintenance for MRIapparatuses, for quickly and efficiently diagnosing faults in an MRIapparatus, and for efficiently repairing faulty MRI apparatuses.

Typically, a service log related to an MRI apparatus, such as a repairlog and/or a performance/maintenance check log, is stored separately bya service provider and a customer. This log is used for various kinds ofinvestigations, such as, for example, to find a cause of a fault thatoccurs in the MRI apparatus. When a fault is detected, the compositionof circuit boards in the MRI apparatus is checked, the variousparameters that may have been adjusted when the apparatus was installedare measured, and a cause for the fault and a malfunctioning part arepinpointed based on information contained in a maintenance manual. Theresult of a scheduled or routine maintenance check may be useful in manycases in determining the cause of the fault and the suspectedmalfunctioning part. However, because the results of such checks orroutine maintenance are not stored in the MRI apparatus, and areretained in separate locations, it is difficult to access these servicelogs and to provide service quickly and efficiently.

There are many different kinds and types of imaging methods that can beemployed in a conventional MRI apparatus. Certain special imagingmethods, such as FASE and EPI, are not used frequently because they arereserved for specific diagnosis. On the other hand, general imagingmethods, such as SE and FSE, are used frequently because they are usedfor routine diagnosis (T1, T2 and 3DMRA, etc.). It is difficult torecognize and determine degradation of the MRI apparatus by merelyviewing images obtained by the general imaging methods (SE, FSE, etc.),as compared with also viewing images obtained using specialized imagingtechniques such as those mentioned above (FASE, EPI, etc.) whichexercise a larger range of performance of the apparatus. Therefore, evenif an image actually indicates some degree of degradation, it isdifficult to determine when or where the degradation of themalfunctioning part started.

Some pulse sequences that are sensitive to the condition of theapparatus are mentioned below.

(1) FSE (ETS more than 15 ms) is sensitive to the state of an eddycurrent, and it manifests itself as non-homogeneous sensitivity in theimage and as variable signal strength in different image slices.

(2) FE-EPI is very sensitive to gradient magnetic field stability,especially offset fluctuation of the gradient magnetic field amplifier,and if there is instability, it manifests itself in the image.

(3) A fat reduction pulse sequence is sensitive to homogeneity of themagnetic field and the remains of eddy currents, and it clearly appearsas uneven fat tissue indications in the image.

(4) A spin-labelling pulse sequence for perfusion imaging is sensitiveto RF magnetic field stability because it measures a difference at thestep of an addition average according to the generating pattern of theRF pulse, and it appears in the Signal to Noise Ratio (SNR).

There are also failure and degradation conditions of the apparatus whichdo not affect the quality of the image directly. In that case, it istime consuming and labor intensive to determine whether the fault ordegradation conditions occurred suddenly or gradually. It is alsodifficult to gather related information.

In clinical inspection, it is rare that RF signals are received on oneWhole Body (WB) coil. Typically, a plurality of different RF coils areused depending upon the part of the body being examined. Some of theseRF coils, for example, those used for the shoulders and for knees, arenot used frequently. Because of their infrequent use, the operationalcondition of these coils, such as achievable SNR, is not always clearbecause they are not checked or observed on a regular basis. Thus, thedetermination that they are out of order typically occurs in an untimelymanner.

As mentioned above, the service log is stored at a service provider anda customer site separately, thus people who require the informationcontained in the service log must contact the service provider sitewhere it is kept. Therefore, in order to ascertain the repair historyand performance check history, or to determine which upgrades oraccessories have been included with a particular MRI apparatus, each ofthese inquiries must be accomplished separately.

Since an MRI apparatus includes many different constituent units, it isdifficult to confirm the part, start time and grade of malfunction whenan imaging fault occurs under, for example, specific image conditions.Therefore, achieving repair becomes time consuming and inefficient. Inaddition, because all log data regarding each apparatus is notconsolidated, it becomes particularly burdensome to statistically manageand upgrade the MRI apparatuses.

Under such conditions, for example, the following problems may occur.

(a) No one may notice that a serviceman may repair the apparatusaccording to incomplete or incorrect information.

(b) Since the serviceman repairs only according to the manual, it maytake considerable time to confirm new troubles which are not describedin the manual.

(c) It is difficult to compare the diagnostic check results of theapparatuses and analyze them to determine a trend of faults ormalfunctions.

(d) Because it is difficult to confirm the upgrade record, theserviceman cannot serve the customer according to the conditionspeculiar to each apparatus.

(e) If the conditions of the apparatus are such that there is thepossibility of an accident or harm to a patient, no one may be alertedto the condition or notice the condition in a timely manner.

(f) It may take considerable time to exchange the units, because anorder for exchange flows by way of the service provider. Exchange ordersoriginate from the customer and are sent to a maintenance center via theservice provider, and exchanges are sent directly from the maintenancecenter to the customer.

SUMMARY OF THE INVENTION

It is an object of the present invention to minimize the time associatedwith an investigation to determine the condition of the apparatus asmuch as possible, accelerate the dispatch of repair units, and repairthe apparatus swiftly. Additionally, it is preferable to determinewhether the trouble occurred suddenly or gradually according to theservice log, and to make this determination accurately. Moreover it ispreferable to anticipate long-term or middle-term troubles at an earlystage by recognizing degradation of the apparatus according to resultsof diagnostic checks, and to prevent future system failures.

According to a first exemplary aspect of the present invention, an MRIapparatus comprises a main unit configured to generate a radiofrequencymagnetic field and receive magnetic resonance signals from an object, ameasurement unit configured to automatically measure at least one of anadjustment value, a state value and an error record of the main unit, aninput device configured to manually input at least one of a software andhardware upgrade record, a customized situation record, a networkconnection record, a repair record, a check record, a maintenance recordand an installation record, and a memory unit configured to consolidateand store measured data from the measurement unit and the input datawith the operation unit.

According to a second exemplary aspect of the present invention, an MRIapparatus comprises a main unit configured to generate a radiofrequencymagnetic field and receive magnetic resonance signals from an object, amemory unit configured to store a schedule of diagnostic imaging tocheck the main unit of the MRI apparatus and a controller configured todirect the operator to prepare diagnostic imaging according to aschedule.

According to another aspect of the present invention, an MRI apparatuscomprises a main unit of the MRI apparatus configured to generate aradiofrequency magnetic field and receive magnetic resonance signalsfrom an object, a memory unit configured to store a schedule of aplurality of imaging methods by which to check the main unit of the MRIapparatus and a controller configured to inform the operator of aphantom used for a particular imaging technique and to direct theoperator to prepare the imaging according to the schedule.

According to another aspect of the present invention, a maintenancesupport apparatus is connected to a plurality of MRI apparatuses andcomprises a communication unit configured to communicate with the MRIapparatus via a communication network, a memory unit configured to storeat least one of an adjustment value, an state value, an error record, asoftware and hardware upgrade record, a customized situation record, anetwork connection record, a repair record, a check record, amaintenance record and an installation record and a controllerconfigured to search data from data stored in the memory unit accordingto the request from the MRI apparatus and send the searched data to theMRI apparatus via the communication unit.

Therefore, both automatically measured data and manually input data canbe obtained swiftly and faults can be recovered quickly or prevented inadvance.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in detail herein with reference to thefollowing drawings in which like reference numerals refer to likeelements, and wherein:

FIG. 1 is a block diagram showing a maintenance support system;

FIG. 2 is a block diagram showing an MRI apparatus, a maintenancesupport apparatus, and a service center apparatus;

FIG. 3 is a flow chart illustrating an exemplary procedure for ascheduled maintenance or performance check of the MRI apparatus;

FIG. 4 is a flow chart illustrating operation of an exemplary embodimentof the invention when trouble occurs;

FIG. 5 is a flow chart illustrating operation of an exemplary embodimentof the invention when an MRI apparatus is upgraded; and

FIG. 6 is an illustrative diagram showing phantoms used for measuringperformance of the MRI apparatus.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

With reference to drawings, an exemplary embodiment of the inventionwill be described herein. FIG. 1 is a block diagram showing amaintenance support system. In this figure, a plurality of MRIapparatuses 100 are connected to a maintenance support apparatus 300 viaa communication network 200, such as, for example, a general public lineor a dedicated line. In addition, a plurality of service centerapparatuses 400 are also connected to the maintenance support apparatus300 via the communication network 200.

The maintenance support apparatus 300 stores data about each MRIapparatus 100. The data relates to all or at least one of adjustment,state of each part, repair, maintenance, check, software and hardwareupgrade, software customizing, error, the conditions at theinstallation, the building construction and the network connection. Theapparatus 300 sends information to the MRI apparatus 100 or the servicecenter apparatus 400 as necessary. Thus the information storedcumulatively is useful and easily accessible at the time various worktakes place, such as, for example, maintenance, repair, and upgrade(renewal and/or addition of a function). The information history recordis hereinafter referred to as apparatus chart information.

The maintenance support apparatus 300 may function as a server, and theMRI apparatus 100 and the service center apparatus 400 which mayfunction as clients receive the apparatus chart information from themaintenance support apparatus 300 as requested or in the case of variouswork described above.

The MRI apparatus 100, the maintenance support apparatus 300, and theservice center apparatus 400 are shown in detail in FIG. 2.

The MRI apparatus 100 includes a main unit 161 which includes magneticcoil assemblies, a computer, etc. The main unit 161 collects RF signalsand reconstructs images. A host controller 103 is connected to the mainunit 161 via a data control bus 113.

An operation unit 104, a display 105, a communication unit 107 forcommunicating with the maintenance support apparatus 300 via theelectronic communication network 200, a self-check control unit 109 forperiodically performing a self-check program, operating the main unit161 and checking a state of main unit 161, and a memory unit 111 whichstores the information about the state, are connected with each othervia the data control bus 113.

The maintenance support apparatus 300 includes a host controller 301. Acommunication unit 309 and an operation unit 303 of the maintenancesupport apparatus 300 are connected to each other via data control bus317. In addition, the apparatus 300 includes a chart generation unit 313generating the apparatus chart information based on the transmittedinformation from a plurality of MRI apparatuses 100 in a contract groupor the service center apparatus 400, a chart database 307 consolidatingand storing the apparatus chart information, and a database controller305 controlling the chart database 307. The apparatus 300 may alsoinclude, an information retrieval unit 311 which retrieves usefulinformation in the chart database 307 responding to a demand from theMRI apparatus 100 or the service center apparatus 400 and an informationprocessing unit 315 which statistically processes the apparatus chartinformation read from the database 307 as service to the MRI apparatus100 or the service center apparatus 400.

The service center apparatus 400, placed in a service center forproviding various services to the MRI apparatus 100, such as maintenanceand repair, has a parts management unit 409 which manages required partspurchase, stock, conveyance, etc. and a service management unit 411which manages a schedule for a serviceman, remote maintenance staff, andmanages the content of an actual maintenance, repair etc.

Next, an exemplary apparatus chart information will be described. Theinformation may include the following various record items describedbelow. Although these items are classified in the categories describedbelow, all items are consolidated and stored together as apparatus chartinformation.

The various adjustment values of the MRI apparatus 100 (RF adjustmentvalue, pulse sequence adjustment value, magnetic uniformity adjustmentvalue, etc.)

The state values of the MRI apparatus 100 (temperature value of eachpart, voltage value of each part, residual value of liquid helium,surrounding temperature, amount of cooling water, etc.)

The repair record of the MRI apparatus 100 (circuit board exchange, itsserial number, etc.)

The maintenance record of the MRI apparatus 100 (charge of the liquidhelium, each part overhaul, etc.)

The check record of the MRI apparatus 100 (result of a scheduled check,etc.)

The software and hardware upgrade record (version record of thesoftware, a type of hardware options, etc.)

The customized situation record (customizing the software, etc.)

The error record (problems, the contents of correspondence, images andparameters at the time of the trouble (however it will be understoodthat this record shall include a mechanism in which all the informationthat specifies a particular patient or patient's information are deletedautomatically from the viewpoint of privacy protection of the patient))

The installation record (date of the installation, SNR, troublegenerated, worker's name, building construction record (a shield roomsketch, a cold-water piping course figure, a power supply constructioncourse figure, other special construction data), etc.)

The network connection record (connection place, connection time,download classification, etc.)

At least four items of the higher ranks of a list (the variousadjustment values, the state values, the repair record and themaintenance record) can be published not only to user who owns theapparatus to which the items relate but also to other users. In order topreserve this published information, the published information cannot bechanged. Accordingly, a record medium or process that prevents suchoverwriting of data may be used.

The information retrieval unit 311 of the maintenance support apparatus300 enables reference to the past apparatus chart information of the MRIapparatus 100 that provided it and similar example reference of otherMRI apparatuses 100.

The maintenance support apparatus 300 provides communication functions(e-mail etc.) with a user (the MRI apparatus 100, the service centerapparatus 400). According to a request for reference check or adjustmentdata from the user, the information processing unit 315 in themaintenance support apparatus 300 may change a normal format of theapparatus chart information to a statistical format, such as, forexample, a graph, so that a user who is familiar to the apparatus canmore quickly and easily understand the situation. Other informationwhere the format can be changed include, for example, temperature datatrend graph, LHe attenuation graph, a magnetic field attenuation graph,a comparison graph with the other apparatus of the adjustment value,etc.

Next, the category of each of the items of the apparatus chartinformation will be described. The items are categorized according to aninput method. One is input manually by the operator and the other isinput automatically by the apparatus. Additionally, manual inputcategories may be classified into a more detailed categories. Forexample, one is input periodically or only once and the other is inputselectively (e.g., on an irregular basis).

The automatically stored items may include, for example, variousadjustment values (RF adjustment value, pulse sequence adjustment value,magnetic uniformity adjustment value, etc.), the state values(temperature value of each part, voltage value of each part, residualvalue of liquid helium, etc.) and error record data (problems, thecontents of correspondence, images and parameters at the time of thetrouble).

The manually stored items that are input selectively, may include, forexample, the software and hardware upgrade record, the customizedsituation record, the network connection record, the repair record(circuit board exchange, serial number, RF coil exchange, etc.). Thecircuit board exchange data may be stored automatically if the circuitboard has a ROM where identification (ID) number is recorded. Inaddition, a serial number bar code may be pasted on the RF coil.

The manually stored items input periodically or only once may include,for example, the check record, the maintenance record and theinstallation record.

Each item of the apparatus chart information can be referred by theservice center apparatus 400 through the communication network 200. Themaintenance support apparatus 300 can provide the information as aprintout, if necessary. The information is consolidated, classified andused, for example, as set forth below.

Repair and error record: A third person (e.g., a service specialist) canconfirm the validity of the repair immediately. Therefore, it becomeseasy to find a repair mistake and prevent a failure expansion after themistake occurs. If the error record is used with other records such asthe state values of the MRI apparatus 100, efficient troubleshooting canbe performed. Furthermore, since the MRI apparatus 100 and the servicecenter apparatus 400 are connected via the communication network 200,when an accident occurs with the MRI apparatus 100, the servicespecialist can access the newest information stored in the maintenancesupport apparatus 300 and repair the MRI apparatus 100. When acomplicated accident occurs, other service specialists can assist usingthe shared information.

If the serious accident that involves a patient, the alert is sent tothe MRI apparatus 100 from the service center apparatus 400, and a userreceives notice of the alert. As soon as the report to the government iscompleted, the same alert is sent to other MRI apparatuses as recall(manual operation or automatically) information, such as readjustment,parts exchange and handling warning. In this manner, similar accidentsmay be prevented.

Maintenance record: In order to maintain the MRI apparatus efficiently,it is necessary to document the current state of the MRI apparatus.Basic data for this is a performance index parameter (an eddy current,T2*, etc.) obtained by the scheduled check described below. Maintenanceis indicated when the value of these index data exceeds a standardvalue, fluctuates in comparison with the stored previous value or tendsto be an unusual value, such as tending upward or downward. For example,because a vacuum tube of a RF amplifier does not usually break suddenly(rather its output typically declines gradually) it may be adjustedaccording to the trend of the value of the transmitting gain by imaginga phantom. If the number of adjustment times is stored, system breakdowncan be prevented by exchanging the vacuum tube before imaging is madeimpossible by vacuum tube failure, for example.

As another example, if the apparatus chart information includinginternal information and external information is similar to apparatuschart information of another MRI apparatus that has been adjusted, theMRI apparatus may be adjusted in the same or similar manner as the otherMRI apparatus. Moreover, the software may be upgraded on basis of theapparatus chart information of an MRI apparatus that is broken.

State values and adjustment values: All of the state values of the MRIapparatus 100, such as temperature value of each part, are fed to theinformation processing unit 315, and as the result, the trend data andthe comparison data with other apparatuses are utilized with the servicecenter apparatus 400. This process may be done automatically.

By analyzing trend data, it is possible to request parts exchange whenthe check value changes or to predict degradation and accident.Moreover, by analyzing the comparison data, it is possible to find anunusual use environment or discover better adjustment values thatimprove the performance of the apparatus 100. For example, the residualquantity of liquid helium for cooling a superconducting magnet ismeasured by the apparatus 100 automatically every day, and the measuredvalue is fed to the maintenance support apparatus 300. It is possible tocalculate the date when the liquid helium should be filled from themeasured values and to report it to a service provider or a user inadvance. Thus, an appropriate service schedule can be achieved. Forexample, the residual quantity of the liquid helium is attenuated 10% inthe first month after a supplement and 20% in the second month, and ifthe cooling is in a dangerous state when it becomes 40% or less, theliquid helium should be filled before the fourth month. As anotherexample, the freezer for cooling a superconducting magnet has mechanicalparts, and it has to be repaired periodically. Although there is a roughestimate of the life of such parts, it changes somewhat with operatingconditions of apparatus. If such mechanisms are repaired after breakingdown, the apparatus cannot be used until repaired. From the user'sperspective, it may cause serious and unexpected damage or delays. If itis repaired too early, a repair term becomes too short resulting ininefficient and expensive operation. Therefore, because it is clear thatthe reduction of the capability of the freezer is influenced by anincrease of temperature, the temperature value is measured periodicallyand automatically. Consequently it is possible to determine a suitablerepair schedule from the periodically measured values as set forthabove.

Upgrade, installation, customized situation, network connection: theseitems are stored as a particular log. Since similar examples can befound, they can be utilized for preventing accidents in newinstallations and for upgrades. Additionally, other items which wererealized during the installation and the upgrade are also recorded.

With respect to the building construction record, when, for example,unusual special work, such as carrying the apparatus on the top floor ofa 20 floor building with a special crane is required, there may be manyattendant problems, including, for example, legal investigation in thecase of using the special crane and examination of the circulationheight difference of cooling water are necessary, for example. Theseproblems and the contents of correspondence, notes, etc. are stored as aparticular log. For example, before cold-water system maintenance etc.,a worker can confirm the procedure of shutting a valve with reference tothis particular log. When a similar situation occurs subsequently, thenotes about the prior special work can be checked in detail by analyzingthis particular log in the maintenance center.

As another example, since MRI apparatus are extremely expensive, theycannot be purchased or replaced frequently. Thus, various hardware andsoftware upgrades are typically performed in order to improveperformance. If an upgrade record is not stored, adverse consequencesmay result from lack of knowledge of previous upgrades when a subsequentupgrade occurs or is scheduled. On the other hand, if an upgrade recordis stored, problems can be anticipated and avoided. For example, whensoftware is upgraded, the load on certain hardware, e.g. the CPU,increases. Hence, if software is upgraded frequently withoutconfirmation of hardware state, it may become impossible to secure therequired speed of operation during clinical use.

Check record: As explained above, there are some cases in whichdegradation of the MRI apparatus 100 can be found only by using aspecific pulse sequence. Therefore, the basic degradation data of theMRI apparatus can be obtained using the specific pulse sequence. When ameasured value using the specific pulse sequence is unusual, or iswithin an acceptable range, but tends toward being unusual, an alert isgenerated and the procedure for repair is started based on thismeasurement.

Before the performance index parameter measured is described, a phantomand the scheduling software themselves are described below. FIG. 6 is anillustrative diagram showing, for example, a pluality of phantoms 510arranged on a phantom rest 520 for measurement by the MRI apparatus. Thephantom rest 520 is arranged on a bed 530 and is secured thereto by, forexample, belts 540. The phantom rest 520 is then introduced to the MRIapparatus via the MRI gantry 500. Of course, it will be understood thatonly one phantom or a plurality of phantoms may be used depending uponthe measurement being made. There are many pulse sequences, one of whichshortens a total imaging time by shortening a repetition time interval(TR) and another of which obtains a large signal by extending TR, suchas, for example, FSE. A phantom material that is adequate appropriatefor T1 enhancement image is one that has a long T1 relaxation time andoutputs a large signal easily with short TR, such as, for example, oil.While, a phantom material that is appropriate for a T2 enhancement imageis one that has a long T2 relaxation time, such as, for example, water.In addition, in order to measure the uniformity of the static magneticfield, a spherical phantom which does not disturb a magnetic field isrequired. Thus, automatic measurement may not work using only onephantom. An appropriate phantom is selected and communicated to anoperator at the end of a day by the scheduling software. The selectedphantom may be one phantom or a plurality of phantoms. If using aplurality of phantoms, such as, for example, shown in FIG. 6, a phantomrest 520 where the phantoms 510 are arranged with the distance betweenphantoms of about 50-70 cm which can separate a sensitive range of theWB coil may be used. The phantom rest 520 is laid on the bed 530 andmoved automatically. As mentioned above, the phantoms 510 are preferablyarranged such that their signals do not interfere with one anther. Thephantom rest 520 may also include indentations or dimples (not shown)along a central axis thereof to prevent the phantoms 510 from fallingoff the rest 520 during measurement. The phantom data is then collectedaccording to the protocol of the scheduling software. When the end of ameasurement day comes, the scheduling software informs the operator andrequests measurement preparation.

Next, the performance index parameter measured for the apparatus chartinformation will be described according to the types of te measurementintervals. For example, there may be three types, one of which ismeasured every time before use (every day), another of which is measuredevery week and another of which is measured every month. Each data ismeasured according to the scheduling software. The data is stored in theMRI apparatus 100 and also in the maintenance support apparatus 300.

An example of data that is measured every day or every other day is dataof a standard picture containing SNR of the WB coil. This measurement isused to check operation of the WB coil itself and the whole system,including transceiver function. This measurement is generally performedby the user every day. The measurement includes obtaining, SNR, signalvalue, noise value, the main frequency of a magnetic field, thetransceiver gain of RF system, the stability of gradient magnetic field,etc. The measurement typically takes about 1 minute, using a phantom,such as, for example, mineral oil, whose T1 term is short. SNR is aparameter by which the state of the whole system can be checkedsynthetically. If SNR is less than the usual value, repair andadjustment are required immediately. In addition, when SNR is unusual asdescribed above, the main cause can be immediately determined byreferring to the signal value, noise value, the main frequency of amagnetic field, and the transceiver gain of RF system. The above signalvalue is a value of SNR and may indicate a signal value on thereconstructed image of the phantom or a signal value beforereconstruction.

The above signal value divided by the receiving gain of RF system is anactual signal value. The signal value typically changes when there is afailure and/or degradation of RF transmitting system, receiving systemand/or degradation of the WB coil. The above noise value is a value ofSNR and may indicate a noise value on the reconstructed image of thephantom or a noise value before reconstruction. The above noise valuedivided by the receiving gain of RF system is an actual signal value.This noise value is not influenced by failure and degradation of RFtransmitting system but is changed by the receiving system anddegradation of the WB coil.

The transmitting gain of the above transceiver gain of the RF system isa parameter which is used for determining the amount of RF transmission.When this value is large, RF electric power supplied to a patient islarge, and when small, supplied RF electric power is small. RF electricpower is fixed using the regular phantom which is checked every day. Thetransceiver gain should be changed according to bodily shape and weightof the patient. Failure and degradation of RF transmitting system can bedetected by this change. The receiving gain of the transceiver of the RFsystem is measured from the signal value of the patient indirectly.Failure and degradation of RF receiving system (besides degradation of areceiving coil itself can be found from the signal value, while failureand degradation of RF transmitting system may be obtained using acertain regular phantom whose characteristics are known.

The above-noted main frequency of a magnetic field is a magneticresonance frequency at the center of the static magnetic field. Theintensity of the static magnetic field can be calculated by Larmorequation based on the main frequency of a magnetic field. In general, amagnetic material (e.g., iron etc.) is used for a magnetic field and amagnetic circuit. The intensity of the static magnetic field changesaccording to the temperature of the magnetic material. When asuperconductive magnet is used, the magnetic field decreases graduallyover time. The stability and the uniformity of the static magnetic fieldare very important parameters in improving quality of an MRI image. If asmall magnetic object, such as a ballpoint pen, is near the MRIapparatus, or a large magnetic object, such as a car, is near an MRIroom, it is possible for the main frequency to change discontinuously.In these cases, there is a strong possibility that the quality of theimage will be degraded, and the cause of this degradation should beidentified and removed immediately. When image quality degrades, andthere is no record of the main frequency of the magnetic field, findingthe cause becomes both time consuming and labor intensive.

It is possible to measure SNR from not only a phantom image using the WBcoil as explained above, but also from a patient image using othercoils. Accordingly, the SNR of other coils may measured without greateffort. For example, the first patient is imaged by using the RF coilunder the condition that RF output is zero in order to measure a noiseof the RF coil itself, and a locater (scout) image is obtained. Thelocater image is used for locating Field of View (FOV), but is not useddirectly for diagnosis. The FOV and other parameters may be fixed inorder to shorten imaging time. Next, the image of the FOV is obtained.Its signal (a fat signal obtained automatically from a fat tissue near abody surface, for example) and the above-mentioned zero RF output noiseare used to measure SNR. The noise may be obtained by subtracting twoindependent images instead of the above-mentioned zero RF output method.In these measurements, not only SNR but also the transmitting gain, thereceiving gain and reflective ratio of RF amplifier may be obtained andstored in the apparatus chart information.

Examples of data that are measured every week by the scheduling softwareare described in further detail below.

One example is eddy current data. In this measurement, a square shapedphantom, for example, including oil is required. The eddy current is aharmful current generated by electromagnetic induction of a metal nearthe MRI apparatus based on switching of the gradient magnetic field. Themain cause is the magnetic leakage from a gradient coil which generatesgradient magnetic field. In recent years, the amount of leakage has beendecreasing due to use of an active shield gradient coil. However, theamount of leakage is not zero, and may be adjusted. The eddy current ofthe conventional MRI apparatus is adjusted along nine axes, X-X, X-Y,X-Z, Y-X, Y-Y, Y-Z, Z-X, Z-Y, and Z-Z, and it decreases less than 1/10to 1/100 in comparison with installation time. However, even in such acase, it turns out that the measured value becomes unstable due tofailure of a gradient coil or its power supply, and the resulting eddycurrent increases. Therefore, short-term stability of the eddy currentis obtained by measuring it many times in one night, and its long-termstability is obtained from a plurality of past records that may bechecked. Thus, the stability of the eddy current may be readjustedperiodically, such as, for example, every week. Since one measurementand adjustment takes about 10 minutes, it is possible to measure andadjust the eddy current automatically many times in one night.

Another example of weekly data is adjustment of the gradient magneticfield. In this measurement, a square shaped phantom including oil, forexample, is required. This adjustment includes adjustment of theintensity and the waveform characteristic of the gradient magneticfield. In the measurement of the intensity of gradient magnetic field, acube phantom, for example, whose side length is accurately known inadvance, is placed such that each side is parallel to X, Y and Z-axisrespectively. In this situation, the phantom is imaged and the sidelength is calculated on the basis of the projection data from eachdirection. The intensity of gradient magnetic field is adjusted suchthat the calculated side length is close to the side length known inadvance.

The waveform characteristic adjustment of the gradient magnetic field isused to correct the amount of distortion at changing points, such as,for example, a standup point of an gradient magnetic field. Thefluctuation of gradient magnetic field is measured from a signal (asignal and phase information) of the phantom, then the amount ofdistortion is compensated. Unless these adjustments are made correctly,the FSE adjustment, EPI delay time adjustment, and FE-EPI time stabilityinvestigation cannot be correct.

Another example of weekly data is FSE adjustment value. In thismeasurement, a square shaped phantom including oil or water, forexample, is required. FSE stands for Fast Spin Echo which is a type ofpulse sequence. In FSE method, it is important to control the phase ofthe repeated echo signal. The FSE adjustment value is evaluatedsynthetically from the delay time of gradient magnetic field system bythe eddy current and the delay time of RF system, etc. This FSEadjustment value includes one value which is relative to the frequencyof a multi-slice and another value which is independent of thefrequency, namely the offset value. These values are expressed as aphase and a phase/frequency, respectively. Since this parameter detectssmall error by a phase value, it is mainly used for checking failure ofthe RF system.

Another example of weekly data is shimming adjustment value. In thismeasurement, a phantom including water, for example, is required. Theshimming adjustment indicates uniformity adjustment of the staticmagnetic field intensity. The uniformity changes based on variousfactors. For example, a change in room layout, small magnetic materialcarried into the room by a patient or an operator, such as, for example,paper clips, that stick to the apparatus, a change in the output of agradient magnetic field power supply or a shimming power supply, ordegradation of a shimming coil or a gradient coil, for example. Sincethere are many factors affecting uniformity of the static magnetic fieldintensity, such as those mentioned above, it is difficult to find theactual cause of any non-uniformity, but it is possible to narrow downthe likely causes by storing periodic data together with the value ofthe above-mentioned main frequency.

Another example of weekly data is EPI delay time adjustment value. Inthis measurement, the phantom is not especially limited. EPI stands forEcho Plainer Imaging. In EPI, a signal is obtained repeatedly by agradient pulse changing at positive/negative after transmitting RF pulseto a patient. The delay time of the echo peak Even/Odd of EPI isgenerated by output distortion of a gradient magnetic field power supplyand the eddy current, especially short-term eddy current caused by RFshield. The EPI delay time can be adjusted by changing RF output timing.

Another example of weekly data is FE-EPI time stability value. In thismeasurement, the phantom shape is not especially limited, but thematerial inside the phantom must be water. FE-EPI time stability valueis evaluated by dynamic study where the same position images of aphantom are repeatedly obtained at predetermined intervals. The level ofN/2 artifacts is measured at two or more points. Failure of a gradientmagnetic field power supply and a gradient coil, and RF shield peeledoff, etc. can be detected using this data.

Yet another example of weekly data is ghost value. In this measurement,the phantom shape is not especially limited and the material inside thephantom may be water or oil. The ghost value is defined as an artifactof the scatter signal to the encoding direction in the background of areconstructed image.

Another example of weekly data is a pair of T1 enhancement image (SE)and T2 enhancement image. An artifact of the T1 image is different froman artifact of the T2 image. In order to obtain a large signal, in T1imaging, an oil phantom should be used, and in T2 imaging, a waterphantom is desirable. Since it is difficult to find a cause at only onemeasurement, these images must be stored.

If it takes a long time to measure a combination of the above-mentionedweekly parameters, the parameters may be measured monthly. In monthlymeasurement, as in the weekly measurement, when a measurement day comes,the scheduling software confirms and at the end of a day, notifies theoperator and requests measurement preparation. The remainder of themonthly procedures are the same as or similar to that of the weeklymeasurement.

The operation of this exemplary embodiment will be described below as ascheduled check with reference to FIG. 2 and FIG. 3. Since the operatingfrequency of a coil or a pulse sequence differs in each hospital, thescheduled check menu is created according to the operating conditions ofa particular unit. For example, in a hospital of cranial neurosurgerywhere the operating frequency of the WB coil is low, the scheduled checkmenu is created such that SNR is measured with a head coil every day,while SNR of the WB coil is measured weekly. Thus, the check of the headcoil is more frequent, and a fault can be found early. The scheduledcheck menu is stored in the self-check control unit 109 of each MRIapparatus 100 as a part of the scheduling software.

The software stored in the self-check control unit 109 recognizes theend of the day when the measurement is planned by, for example,detecting an off-command operation by the operator, such as shutdown viathe operation unit 104. Such a notification including a type of imagingmethod is displayed on the display 105 in step 1. The specified phantomcorresponding to the imaging method is also displayed on the display 105in step 2. After the operator completes preparation, phantom imagingstarts using a specified imaging method, parameters of the system areautomatically measured and adjusted by the software in step 3. Asmentioned above, if the phantom rest which moves automatically is used,the operator may not wait during the phantom imaging, and automaticmeasurement and adjustment is possible at any time, such as, for examplea period of low use, for example, midnight. After the measurement iscompleted, each parameter is adjusted, if necessary, and a result of themeasurement and adjustment is fed to the maintenance support apparatus300 via the communication network 200. In the maintenance support center300, this result is stored in the apparatus chart information in step 4.When requested by the operator, the result itself and analysis data aretransmitted and immediately communicated to the operator. The operatoris notified via the display 105. If the software has an analyzingfunction, an easy to read form of analysis data, such as, for example,graphical representation of the data, may be generated by the softwarein the MRI apparatus 100.

The scheduled check is linked to its result report. For example, onFriday the scheduled check is performed after the operator sets thephantom according to the request of the software, and the result reportis displayed on a display in the hospital on Monday. In addition, emailnotification may be sent to the operator, an engineer, a chief engineer,etc. automatically.

When the state of apparatus is still poor, the state is classified intothe following groups according to the content of the failure and noticethe group to the operator. First, use of the MRI apparatus is prohibitedcompletely when the failure may harm the patient or cause a seriousdamage to the MRI apparatus. Second, when the failure may harm thepatient or cause a serious damage to the coil itself, the use of aspecific coil is restricted until an alternative coil is prepared.Third, the use of a specific pulse sequence is restricted when thefailure may cause an insufficient image. Fourth, the use of a specificimaging method is restricted when the failure may cause a bad image.Additionally, the group of the failure may be displayed on the displayin the hospital and may be sent to the operator, the engineer, the chiefengineer, etc. by email. When the state of the apparatus is poor, asdescribed above, a request for imaging the phantom in order to confirmthe failure may be sent to the operator. This is especially useful fordetermining failure of the coil.

Next, the operation at a failure state will be explained below withreference to FIG. 4. In order to prevent an accident, when themaintenance support apparatus 300 finds a serious error among the errorrecord or a failure image is found by the operator, the maintenancesupport apparatus 300 receives the failure image and transmits ittogether with the chart apparatus information to the service centerapparatus 400 in step 1.

A troubleshooter in the service center 400 checks the transmitted imageand the chart information in step 2 and accesses the chart database 307in the maintenance support apparatus 300 in order to search for asimilar case in step 3. The troubleshooter analyzes the chart and listspossible causes for the failure in order in step 4. The troubleshootercontacts a service provider which supports the hospital, and ordersrepair parts and staff in step 5. At this time, the troubleshooter orthe repair staff of the service provider reports the result of initialinvestigation and notices expectation of the repair to the operator inthe hospital via a communication network, etc. In addition, if failureimages were obtained in a similar imaging method in the same MRIapparatus, the troubleshooter may propose that the operator use anotherimaging method, if possible. Furthermore, if the failure is temporary orcan be avoided by an update of the software, the troubleshooter may askthe operator to image the phantom after changing the software in orderto confirm that the MRI apparatus has recovered from the failure. Thetest image of the phantom is transmitted to the service center 400 viathe maintenance support apparatus 300 and the troubleshooter can checkit and confirm recovery in step 6. The above-mentioned procedure isstored in the database in the maintenance support apparatus 300 toprevent re-failure in step 7.

If the failure is not temporary and repair staff is required, thefollowing procedure may, for example, be performed. The repair parts areordered based on the cause of the failure, the repair staff of theservice provider is requested, the order letter for the repair staff isgenerated according to the above-mentioned cause list. After theseprocesses are completed, the repair staff contacts the operator. If thespare time data (i.e., times when repairs can be made) is stored in theMRI apparatus in advance by the operator, the repair staff may check itbefore contact. In such a case, if the failed imaging method is rarelyused, the spare time may be given priority. On the other hand, if thefailed imaging method is used frequently, the repair staff may requestthat the operator take a repair time without considering the spare time.The repair staff repairs the MRI apparatus quickly by referring to theapparatus chart information in the maintenance center 300 from the MRIapparatus 100. Additionally, the troubleshooter may ask the operator toimage a phantom as mentioned above, before the repair staff comes to thehospital. In this imaging, a pulse sequence where variations of data canbe visible by turning off the gradient magnetic field in the phaseencoding direction or a pulse sequence where the sensitivity unevennessof FSE can be measured is used, for example.

In the case of repair, the apparatus chart information is of great use.Most troubles are caused by heavy use of the MRI apparatus 300 oradverse environmental conditions, for example, when there is particularproblem depending on the hospital. As an example, when moving a largeexternal magnetic object after adjusting the uniformity of the staticmagnetic field, a pulse sequence which is sensitive to fluctuation ofthe uniformity, such as EPI and fat control is used. As another example,when another apparatus like an X-ray CT apparatus is being operated andthe MRI room is not shielded completely, and a pulse sequence which issensitive to noise is used. Since it is difficult to collect outsideenvironment data by the MRI apparatus 100, the maintenance supportapparatus 300 obtains it cooperating with a hospital and extracts onlyuseful data for repairing. Moreover, the fault can be found more quicklyby comparing with other accumulated data from other MRI apparatuses.

Next, an upgrade operation will be described below with reference toFIG. 5. For example, when a new highly accurate imaging method (newpulse sequence, etc.) is developed, the MRI apparatus may be upgradedwith new software. The upgrade information is stored in the maintenancesupport apparatus 300 and the operator can check it anytime. Ifnecessary, the operator contacts the maintenance support apparatus 300via the communication network 200 in step 1. The maintenance supportapparatus 300 determines whether the upgrade is appropriate or not. Inparticular, upgrade staff in the maintenance support apparatus 300accesses the apparatus chart information in step 2. The staff determineswhether the required upgrade is suitable for the MRI apparatus 100 and,if suitable, the appropriate conditions of the upgrade, such as, forexample, download speed in step 3. After setting the condition, themaintenance support apparatus 300 sends the upgrade software to the MRIapparatus 100 in step 4. The upgrade information is stored in the chartdatabase 307 in step 5. The MRI apparatus may temporarily use both oldand new software until a relation of data measured by both softwareversions becomes clear. After the evaluation of the relation, only thenew software is used.

As another example, the above described apparatus chart information canbe used for parts dispatch. In particular, the parts management unit 409in a service center 400 orders to dispatch parts automatically on basisof the apparatus chart information from the maintenance supportapparatus 300.

As described in the above exemplary embodiments, since data inputmanually by the operator and data measured automatically by theapparatus are consolidated and stored, when the failure occurs, thediagnostic investigation of the MRI apparatus by the operator can beminimized as much as possible or the failure can be prevented inadvance.

While the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, the exemplary embodiments of the invention, as set forthherein, are intended to be illustrative, not limiting. Various changesmay be made without departing from the true spirit and full scope of theinvention, as defined in the following claims.

1. A system for maintaining and supporting an MRI apparatus, comprising:a plurality of MRI apparatuses; a maintenance support apparatus forstoring data relating to each MRI apparatus; a plurality of servicecenter apparatuses, each for supporting maintenance and repair of atleast one MRI apparatus; and a communication network for providing acommunication connection between said MRI apparatuses, said maintenancesupport apparatus and said service center apparatuses, wherein at leastone of said MRI apparatuses comprise: a memory unit configured to storean imaging schedule used to check a main unit of the MRI apparatus; anda controller configured to instruct an operator to prepare imagesaccording to the schedule, wherein the controller instructs the operatorto prepare a first image for evaluating signal to noise ratio of a wholebody coil of the main unit at a first regular interval and a secondimage for evaluating at least one of an eddy current, FSE adjustment,shimming adjustment, EPI delay time adjustment, FE-EPI time stability,ghost and sensitivity unevenness of FSE at a second regular interval. 2.A system according to claim 1, wherein at least one of said plurality ofMRI apparatuses comprise: a measurement unit configured to measure atleast one parameter of a main unit of an MRI apparatus automatically; aninput device configured manually input at least one record of the mainunit; and a memory unit configured to consolidate and store theparameter measured by measurement unit and the manually input data.
 3. Asystem according to claim 2, wherein said parameter includes at leastone of an adjustment value, a state value and an error record of themain unit, and said record of the main unit includes at least one of asoftware and hardware upgrade record, a customized situation record, anetwork connection record, a repair record, a check record, amaintenance record and an installation record.
 4. A system according toclaim 1, wherein said data comprises apparatus chart information.
 5. Asystem according to claim 4, wherein said apparatus chart informationincludes at least one of at least one of an adjustment value, a statevalue and an error record of the main unit, and a record of the mainunit including at least one of a software and hardware upgrade record, acustomized situation record, a network connection record, a repairrecord, a check record, a maintenance record and an installation record.